Surface elevation profile measuring device

ABSTRACT

For use in combination with the slip form paver, a device for detecting, measuring and recording surface irregularities of freshly formed pavement still in a plastic condition. A counterweighted pan float lightly engages the pavement surface and responds to irregularities by reciprocal movement as the paver advances over the grade surface. The pan is suspended from an interconnecting truss structure of the trailing forms of the paver which provides a mobile reference plane parallel to the grade engaging surfaces of the trailing forms and paver. A chart recorder driven by a grade engaging wheel provides a continuous, permanent record of the surface irregularities detected by the pan float.

United States Patent Anderson et al. [4 1 July 11, 1972 s41 SURFACE ELEVATION PROFILE 1,237,735 8/1917 Wright ..33/126.6 MEASURING DEVICE 2,344,216 3/1944 Raydon ..33/l74 R [72] Inventors: John E. Anderson; Homer Dayle Slnneu, pfimary Examine, Lena1-d puma both of Lmcoln' Nebr' Assistant xaminerl aul G. Foldes [73] Assign: state of Nebraska Arromey-Scofield, Kokjer, Scofield & Lowe [22] Filed: Nov. 26, 1969 [57] ABSTRACT [2 APP 830,162 For use in combination with the slip form paver, a device for detecting, measuring and recording surface irregularities of freshly formed pavement still in a plastic condition. A counterweighted pan float lightly engages the pavement surface [58] Field "33/174 R 2 144446 and responds to irregularities by reciprocal movement as the paver advances over the grade surface The pan is suspended 33/1266 37/D1G 94/46 46 R from an interconnecting truss structure of the trailing forms of the paver which provides a mobile reference plane parallel to [56] References Cited the grade engaging surfaces of the trailing forms and paver. A UNITED STATES PATENTS chart recorder driven by a grade engaging wheel provides a continuous, permanent record of the surface irregularities de- 3,257,917 6/1966 Lewis ..94/46 R meted by the pan fl t 2,491,275 12/1949 Millikin.. .....94/46 R 3,466,990 9/1969 Toles ..94/46 R 8 China, 7 Drawing figures PATENTEDJUL 1 1 I972 SHEET 10F 2 Sag C INVENTOR Jo/m i. finaenson Homer 0. Sinner? i. ATTORNEKS SURFACE ELEVATION PROFILE MEASURING DEVICE BACKGROUND OF THE INVENTION In the construction of modern highways, it is common practice to use a road surfacing machine known in the art as a slip form paver. The foundation of the highway to be constructed is carefully compacted and cut to exact grade line. The slip form paver advances over this grade surface, laying a continuous pavement slab, typically 24 feet in width.

Extending rearwardly from each side of the paver are long trailing forms which slide along the grade surface and engage the sides of the pavement slab. interconnecting truss structures, extending laterally above the pavement surface, rigidly attach to the trailing forms and prevent the slab from spreading laterally. Since the slip form paver advances at a relatively slow rate of speed, the trailing forms provide sufficient holding time, usually 8 to 12 minutes, for the pavement to reach a condition such that the slab shape will be retained as the pavement permanently hardens. Normally, a burlap drag is attached to the end of the trailing forms, the drag engaging the pavement and imparting the final finish to the surface.

In order to evaluate the highway so constructed from the standpoint of safety and comfort for future users, various devices are employed to provide an elevation profile of the surface irregularities. A common feature in such devices is to measure the elevations and depressions of the highway relative to a reference plane created by a multiwheeled vehicle with an elongated wheel base moving over the highway surface.

Unfortunately, the multiwheeled vehicle can travel over permanently hardened pavement only. Should the measuring device detect an irregularity not meeting the acceptable standards of safety and riding comfort, improvement to the surface characteristics represents substantial and elaborate repair because the pavement has permanently hardened.

SUMMARY OF THE INVENTION The primary purpose of this invention is to provide a surface elevation profile measuring device for operation in conjunction with a slip form paver and capable of detecting and measuring surface irregularities of pavement in a plastic condition. The foremost benefit derived from this device is the immediate, "on the spot" analysis of the pavement slab as it is formed. Adjustments can be made to the paving machine, as required, and the quantitative effect of those adjustments can be observed and evaluated. Likewise, a direct benefit from this device is that immediate detection and measurement of elevations and depressions can serve as a basis for correction of these irregularities while the pavement is still in a workable plastic condition.

Another object of the invention is to provide a surface elevation profile measuring device operable to accurately detect and measure elevations and depressions of freshly formed pavement relative to a mobile reference plane parallel to the grade engaging surfaces of the slip form paver.

Another object of the invention is to provide a surface elevation profile measuring device operable to indicate an amplitude modified profile of surface irregularities detected by a pan float lightly engaging surface.

A further object of the invention is to provide a surface elevation profile measuring device having a recording unit to make a permanent, continuous chart corresponding to the pavement surface profile. A wheel engaging the grade surface provides advancement of the chart synchronized with the forward progress of the paver. In addition to immediate analysis of the surface characteristics, the chart may serve as a useful teaching and designing aid for the construction of future highways.

Other and further objects of the invention, together with features of novelty appurtenant thereto, will appear in the course of the following description.

SIIII DESCRIPTION OF THE DRAWINGS In the drawings which form a pan of the instant specification and are to be read in conjunction therewith, and in which like reference numerals indicate like parts in the various views:

FIG. 1 is a side elevational view of a surface elevation profile measuring device constructed in aecordancewith a preferred form of the invention and operatively connected to the trailing forms of a typical slip form paver, the measuring device shown slightly enlarged;

FIG. 2 is an enlarged sectional view along line 2-2 of FIG. 1 in the direction of the arrows, the break lines indicating interrupted length;

FIG. 3 is an enlarged fragmentary view, partly sectional, taken along line 3-3 of FIG. I in the direction of the arrows;

FIG. 4 is a side, partly sectional view along line 44 of FIG. 3 in the direction of the arrows;

FIG. 5 is a greatly enlarged front perspective view of the measuring device;

FIG. 6 is an enlarged, fragmentary plan view along line 6-6 of FIG. 4 in the direction of the arrows; and

FIG. 7 is an enlarged, fragmentary front view along line 7- 7 of FIG. 4 in the direction of the arrows.

Referring to FIG. I, a slip form paver, generally designated numeral 10, is shown disposed on a previously prepared grade surface 11. The arrow A indicates the direction of travel when paver 10 advances along the grade 11 preparing a pavement slab. A portion of the slab previously prepared is shown at the far left ofFIG. lat 12.

Extending rearwardly from each side of the paver 10 are trailing forms 13 having a bottom surface 13a engaging the grade II and one side 13b engaging the freshly formed pavement l2. Spaced along the length of each trailing form 13 are a plurality of vertical posts 14. Opposed posts I4 on the respective trailing forms are rigidly connected by a truss structure 15, as best viewed in FIG. 2. The truss structures 15 prevent the trailing forms 13 from being forced outwardly by the fresh pavement 12.

The surface elevation profile measuring device 16 now to be described is shown operatively connected to one such truss structure 15 interconnecting the trailing forms.

Engaging the surface I! of the fresh pavement issuing from the paver is a pan-shaped flat 18 from the center of which a rod 19 extends upwardly and substantially perpendicular to the pavement surface 17. The rod 19 passes axially through a vertical sleeve 20 connected to the truss structure 15 by a sleeve bracket 2!. The bore of the sleeve 20 is of sufficient diameter to allow free reciprocation of the rod 19.

Attached to the uppermost end of the sleeve 20 is an L- shaped bracket 21 having an associated idler pulley 22. The pulley 22, which has a circumferential groove, is disposed above the end of the sleeve 20 and the edge portion 22a of the pulley located above the sleeve 20 is aligned with the axis of rod 19. The grooved edge of pulley 22 receives a tension cable 23 which is attached to the uppermost end of rod 19.

Also connected to the truss structure 15, but remote from the sleeve 20, is an upright standard 24 projecting above the truss structure and substantially perpendicular to the pavement surface 17. The standard 24 is attached to the upper and lower members of the truss structure 15 with fittings 25 or other suitable attachments. Disposed on the upper end of the standard 24 is a chart recorder 26 later to be described.

Beneath the chart recorder 26 is located a double pulley 27 having a smaIl rim 27a and a large rim 27b, each of which is grooved about its rim to receive a wire cable. The tension cable 23 attached to the rod 19 of the pan float loops around the small rim 27a and suspends a counterweight 28, having an upright extension 29. Attached near the lower end of the standard 24 is a U-shaped guide member 30 which extends outwardly in such a fashion that the extension 29 of the counterweight is located between the prongs of the guide member 30.

The pan float l8, counterweight 29, tension cable 23, and double wheel pulley 27 form a suspension system. When the pan float 18 (which weights slightly more than the counterweight and thus bears lightly against the pavement) is displaced upwardly, the counterweight 28 in response moves downwardly and the double pulley 27 is rotated by the tension cable 23 acting on the circumferential edge 27a in a clockwise direction as viewed in FIG. 3. n the other hand, when the pan float moves downwardly, the counterweight 28 in response is pulled upwardly and the double pulley 27 is correspondingly rotated in a counterclockwise direction as viewed in FIG. 3.

In the preferred embodiment of the invention, the weight of counterweight 28 in relation to the weight of the pan float I8 is such that the bearing load on the pavement surface 17 caused by the pan float is no more than one ounce per square inch.

As previously mentioned, a chart recorder 26 is located on the upper end of the upright standard 24. Located above the recorder 26 is a pulley 31 which is preferably the same diameter as the large rim 27b of the double pulley 27 and which is grooved about its rim to receive a wire cable. An endless cable 32 is drivingly supported on and between the large rim 27b or the double pulley 27 and the pulley 31.

The chart recorder 26 has a continuous paper supply roll 34. Located on the face 33 of the recorder and traversing the width of the supply paper 34 is a channel guide bar 35. Slidably mounted and retained within the guide bar 35 is an indicator member 36 attached to the endless cable 32. Member 36 is thus supported for reciprocal movement throughout the length of the guide bar 35 in response to movement of the endless cable 32.

A stylus 37, which has a self-contained marking supply such as ink, dye, or graphite, is firmly held by the indicator number 36 and in marking contact with paper 34.

The chart recorder 26 has a roller drive whereby the supply paper 34 can be advanced past the stylus 37. When the paper 34 is advanced in conjunction with reciprocal movement of the indicator member 36 within the guide bar 35, the stylus 37 leaves a continuous trace 38 which graphically represents such movements.

The schematic arrangement of rollers for advancing the paper 34 past the stylus 37 is shown in FIG. 6. The supply roll 34 of chart paper, as viewed in the upper right-hand corner of FIG. 6 is disposed on the feed post 40 of the recorder. Paper 34 is fed from the supply roll 34 around the first guide roller 40 and passes between the stylus 37 and a writing support surface 42 forming part of the recorder. The paper 34 then passes around a second guide roller 43, around a tension roller 44, and finally to the take-up roller 45. The paper 34 is advanced by rotating the take-up roller 45 in a counterclockwise direction as viewed in FIG. 6. Rotation of the take-up roller 45 causes the supply roll 39 on the feed post 40 to rotate in a counterclockwise direction and movement of the paper 34 across the first guide roller 41 causes the latter to rotate in a clockwise direction, the second guide post 43 to rotate in a clockwise direction, and the tension roller 44 to rotate in a counterclockwise direction. The paper 34 is kept taut across the writing support surface 42 by friction between the feed post 40 and the supply roll 39 and also by the tension roller 44.

The take-up roller 45 is rotated in synchronism with the forward progress of the paver 10. To accomplish this, a grade engaging wheel 46 is mounted on rotary shaft 47 extending from a reduction box housing 48 mounted on the outer side of the trailing form 13. The grade engaging wheel 46 rotates as the paver and trailing forms advance along the grade surface 1 1.

Within the reduction box housing 48 is a small pulley 49 keyed to shaft 47. Also disposed within the housing 48 is a larger pulley 50 fixedly mounted on a shaft l, one end of which extends through the reduction box housing. An endless belt 52 drivingly connects pulleys 49 and 50. (It will be understood that sprockets and a drive chain will also serve.) Connected with the shaft 51 is a flexible cable-type drive shaft 53 extending to the chart recorder 26 where it is connected to the take-up roller 45.

In operation, the surface elevation profile measuring device is used in combination with the slip form paver in the manner to be described.

As the slip form paver l0 advances along the grade surface 11 preparing a continuous pavement slab 12, the pan float l8 lightly engages and advances over the fresh pavement surface 17. The truss structure 15 and trailing forms 13 provide a mobile reference plane parallel to the grade surface 11 from which the pan float l8 detects surface elevations and depressions.

During the advancement of the pan float 18 over the pavement surface l7 with the forward progress of the paver 10, the supply paper 34 of the chart recorder 26 is advanced past the stylus 37 by the rotation of the grade engaging wheel 46, which is transmitted through the pulley 49, endless belt 52, large fly wheel 50 and flexible drive shaft 53 to the takeup roller 45. If no surface irregularities are detected by the pan float 18, the stylus 37 leaves a substantially straight, longitudinal trace 38 on the supply paper 34; the hypothetical straight trace represents the profile of what is termed as the mobile reference plane.

However, assuming that the measuring device 16 is being advanced over an elevation in the pavement surface 17 relative to the mobile reference plane, the pan float 18 is displaced upwardly which causes the rod 19 of the pan float to move upwardly within the guide pipe 20. As previously noted in this situation, the counterweight 29 descends and, by reason of the tension cable 23 looped around the small pulley 27a of the double pulley 27, the latter rotates in a clockwise direction as viewed in FIG. 3. This, in turn, acting through endless cable 32, causes the indicator member 36 and stylus 37 to move upwardly in the channel guide bar 35, making a corresponding upward mark on the supply paper 34 of the chart recorder.

When the pan float 18 is advanced past the elevation in the pavement surface, the float drops back downwardly, causing counterclockwise rotation of the double wheel pulley as viewed in FIG. 3 and thereby causing the stylus 37 to leave a corresponding downward mark on the supply paper 34. Since the paper 34 is advanced past the stylus 37 as the latter moves in reciprocal fashion in the channel guide bar 35, the trace 38 representing the surface elevation profile is in the form of an inverted V above the hypothetical straight longitudinal trace representing the mobile reference plane.

If a depression in the pavement surface relative to the mobile reference plane is encountered, the reverse of the above operation occurs and the pan float 18 is displaced downwardly causing a corresponding downward mark to be made on the supply paper 34 by the stylus 37.

In the preferred embodiment of the invention, the trace 38 on the supply paper 34 is amplitude. The lateral lengths of the amplitudes on the trace from the substantially straight, longitudinal trace representing mobile reference plane are true heights and depths of pavement elevations and depressions relative to the mobile reference plane multiplied by a factor equal to the ratio of the diameter of the large rim of the double pulley 27 over the diameter of the small rim. Although the chart recorder 26 is beneficial to provide a permanent representation of the surface profile, it should be recognized that the chart record is not essential to the operation of the surface elevation profile measuring device. With the chart recorder disconnected, the reciprocal movement of the indicator member 36 provides visual indication of the surface profile.

From the previous description, it will be seen that this invention greatly benefits the construction of modern highways by detecting and measuring surface irregularities of freshly formed pavement. This device provides an immediate analysis of the perfonnance of a slip form paver and serves as a basis for correction of surface irregularities while the pavement is still in a workable plastic condition.

In the preferred embodiment of the invention, 300 inches of forward progress by the paver results in one inch of advancement of the paper 34 past the stylus 37. However, it is significant to note that this is merely a matter of design choice and the advancement of the paper relative to the forward progress of the paver can be synchronized to any desirable ratio by using an appropriate combination of diameters for the rotatable members previously described.

In addition, this device provides a continuous, permanent record of the surface characteristics of the pavement slab which can serve as a useful designing and teaching aid in the construction of future highways.

From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth, together with other advantages which are obvious and which are inherent to the structure.

It will be understood that certain features and combinations are of utility and may be employed without reference to other features and subcombinations.

Since many possible inventions may be made of the invention without departing from the scope thereof, it is understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Having thus described my invention, I claim:

1. In combination, a slip form paver having grade engaging trailing forms and operable to advance over a grade surface preparing a continuous slab of freshly formed pavement and a surface elevation profile measuring device to detect and measure surface irregularties of the freshly formed pavement put down by said paver, said measuring device comprising:

referencing means providing a mobile reference plane parallel to a reference plane defined by the grade engaging surfaces of said paver and said trailing form;

detecting apparatus connected to said trailing forms including a float member lightly engaging said freshly formed pavement and advanced on said pavement by the forward progress of said paver over said grade surface, said float member operable for reciprocal movement when advanced over surface irregularties relative to said mobile reference plane; and

an indicating apparatus connected with said detecting apparatus remotely from said float member and operable to visually indicate surface irregularties relative to said mobile reference plane in responce to the reciprocal movement of said float member.

2. A combination as in claim I, wherein said float member bears on said pavement with a maximum force of l ounce per square inch.

3. A combination as in claim I, said detecting apparatus including detecting pulley means operable to rotate in response to reciprocal movement of said float member and said indicating apparatus including indicating pulley means connected to said detecting pulley means and operable to rotate in response to rotation of said detecting pulley means.

4. A combination as in claim I, said indicating apparatus including amplitude modification means connected to said detecting apparatus to provide an amplitude modification response to reciprocal movement of said float member.

5. A combination as in claim 4, said detecting apparatus including detecting pulley means operable to rotate in response to reciprocal movement of said float member and said amplitude modification means including indicating pulley means larger in diameter than said detecting pulley means, said indicating pulley means connected to said detecting pulley means in order to rotate in response to rotation of said detecting pulley means.

6. A combination as in claim 1, said indicating apparatus including a recording assembly comprising:

a stylus operable for reciprocal movement in response to reciprocal movement of said float member;

markable material disposed under said stylus in engaging fashion to receive imgressionsfrom said stylus; and roller means associate with said marking material to advance said material past said stylus.

7. A combination as in claim 6, said recording assembly including synchronizing means to operate said roller means in order to advance said markable material past said stylus in response to forward progress of said paver.

8. A combination as in claim 7, said synchronizing means including a grade engaging wheel connected to one said trailing form and operable to rotate in response to forward progress of said paver and a flexible drive shaft associated with said wheel to transmit rotation to said roller means. 

1. In combination, a slip form paver having grade engaging trailing forms and operable to advance over a grade surface preparing a continuous slab of freshly formed pavement and a surface elevation profile measuring device to detect and measure surface irregularties of the freshly formed pavement put down by said paver, said measuring device comprising: referencing means providing a mobile reference plane parallel to a reference plane defined by the grade engaging surfaces of said paver and said trailing form; detecting apparatus connected to said trailing forms including a float member lightly engaging said freshly formed pavement and advanced on said pavement by the forward progress of said paver over said grade surface, said float member operable for reciprocal movement when advanced over surface irregularties relative to said mobile reference plane; and an indicating apparatus connected with said detecting apparatus remotely from said float member and operable to visually indicaTe surface irregularties relative to said mobile reference plane in responce to the reciprocal movement of said float member.
 2. A combination as in claim 1, wherein said float member bears on said pavement with a maximum force of 1 ounce per square inch.
 3. A combination as in claim 1, said detecting apparatus including detecting pulley means operable to rotate in response to reciprocal movement of said float member and said indicating apparatus including indicating pulley means connected to said detecting pulley means and operable to rotate in response to rotation of said detecting pulley means.
 4. A combination as in claim 1, said indicating apparatus including amplitude modification means connected to said detecting apparatus to provide an amplitude modification response to reciprocal movement of said float member.
 5. A combination as in claim 4, said detecting apparatus including detecting pulley means operable to rotate in response to reciprocal movement of said float member and said amplitude modification means including indicating pulley means larger in diameter than said detecting pulley means, said indicating pulley means connected to said detecting pulley means in order to rotate in response to rotation of said detecting pulley means.
 6. A combination as in claim 1, said indicating apparatus including a recording assembly comprising: a stylus operable for reciprocal movement in response to reciprocal movement of said float member; markable material disposed under said stylus in engaging fashion to receive impressions from said stylus; and roller means associated with said marking material to advance said material past said stylus.
 7. A combination as in claim 6, said recording assembly including synchronizing means to operate said roller means in order to advance said markable material past said stylus in response to forward progress of said paver.
 8. A combination as in claim 7, said synchronizing means including a grade engaging wheel connected to one said trailing form and operable to rotate in response to forward progress of said paver and a flexible drive shaft associated with said wheel to transmit rotation to said roller means. 